1. Field of the Invention
The present invention generally relates to deflector rolls for conveying strip material and, more particularly, to quadrant roll conveyors with strip centering action for conveying strip material.
2. Description of the Prior Art
In the relevant industry, xe2x80x9cquadrant rollsxe2x80x9d or xe2x80x9cbasket rollsxe2x80x9d have been used to replace deflector rolls and, in particular, deflector rolls of large diameter. A quadrant roll or basket roll unit is normally an assembly of small diameter rolls mounted on two side frames, with the rolls positioned on the theoretical contour of a sector, or quadrant, of the deflector roll to be replaced. FIG. 1 shows a typical deflector roll 2 and a typical quadrant or basket roll unit 4 intended to replace the deflector roll 2.
It is known in the art to position rolls in horizontal roll conveyors in a xe2x80x9cherringbonexe2x80x9d or xe2x80x9cchevronxe2x80x9d configuration. A typical herringbone-type horizontal roll conveyor is disclosed by U.S. Pat. No. 1,863,520 to Camerota. The horizontal roll conveyor disclosed by the Camerota patent includes two sets of oppositely facing rolls, with each set of rolls inclined at an angle relative to a centerline of the horizontal (flat) roll conveyor. The Camerota patent further discloses that the herringbone-type configuration provides a centering action to objects carried by the horizontal roll conveyor. In the case of the Camerota patent, the objects to be transported are cylindrical-shaped objects such as metal pipe. The rolls in the horizontal roll conveyor disclosed by the Camerota patent are driven.
FIG. 2 of the present application illustrates the principle behind the self-centering action provided by a horizontal roll conveyor with herringbone-arranged rolls. FIG. 2 is a plan view schematically showing a typical herringbone-type horizontal roll conveyor designated by reference numeral 10. A plurality of cylindrical rolls 12 is positioned to the left and right side of centerline Axe2x80x94A of the horizontal roll conveyors 10. Each of the rolls 12 is positioned at an angle xcex2 relative to the centerline Axe2x80x94A of the horizontal roll conveyors 10. A strip 14, such as a metal strip, is positioned on the rolls 12. In FIG. 2, the strip 14 is shown centered to the centerline Axe2x80x94A of the horizontal roll conveyors 10.
Generally, if the strip 14 is centered on the horizontal roll conveyors 10, the weight of the left side of the strip 14, designated by reference numeral 16, is equal to the weight of the right side of the strip, designated by reference numeral 18. Consequently, the weight of the strip 14 resting on the left and right side rolls 12 is the same. When the strip 14 is in running condition and centered, the rolls 12 generate on the strip 14 identical horizontal and opposite forces F2 and H2. Forces F2 and H2 are proportional to the weight of the strip 14 resting on the rolls 12 and the frictional coefficient between the strip 14 and the rolls 12, as is well known in the art. When the strip 14 is not centered with the centerline Axe2x80x94A of the horizontal roll conveyors 10, the rolls 12 generate opposite but unequal forces F2, H2, which result in a concurrent centering action urging the strip 14 to a centered position on the horizontal roll conveyors 10. V1 in FIG. 2 represents the direction of travel of the strip 14. In FIG. 2, reference character F represents the force acting on the left side 16 of the strip 14, with reference characters F1, F2 representing the vector components of force F. Likewise, reference character H represents the force acting on the right side 18 of the strip 14, with reference characters H1, H2 representing the vector components of force H, as will be appreciated by those skilled in the art.
Heretofore, the above-discussed xe2x80x9cherringbonexe2x80x9d or xe2x80x9cchevronxe2x80x9d principle has not been applied to quadrant roll conveyors, also known as xe2x80x9cbasket roll unitsxe2x80x9d, where the weight of the strip 14 in FIG. 2 (i.e., the pressure of the strip 14 on the rolls 12) is replaced by strip tension, generating pressure on the rolls. In a quadrant roll with chevron rolls, as strip tension increases also pressure and centering forces increase. In a flat, horizontal roller conveyor as strip tension increases, pressure on the roll is less with less centering effect.
The present invention has as its object to provide a quadrant roll conveyor with strip centering action for conveying strip material.
The present invention is a quadrant roll conveyor for conveying strip material, such as metal, plastic or paper. The conveyor generally includes at least three substantially parallel support members on a frame for supporting a plurality of rolls around a quadrant roll of any desired wrapping angle, with the intermediate support members positioned on the center of the strip conveying system. The quadrant roll conveyor further includes a plurality of rolls, with each of the rolls journaled for rotation in the support members. The rolls are positioned on opposed sides of the conveyor centerline. The rolls are each positioned at an angle of less than 90xc2x0 with the conveyor centerline to define a chevron pattern around the wrapping angle. The strip material is displaced in center position on the conveyor by the rolls or pushed to the center each time the strip is out of center.
The rolls are preferably rounded or crowned along the longitudinal centerline, but may also be tapered. The rolls may also have a first portion in the longitudinal direction that is cylindrical and a second portion in the longitudinal direction that is tapered.
Additionally, the rolls may be positioned on the opposed sides of the conveyor centerline such that each roll has an axis of rotation intersecting the axis of rotation of a corresponding roll located on the opposite side of the conveyor centerline. The axes of rotation of the oppositely facing rolls preferably intersect at a point in vertical plane passing through the conveyor centerline. Alternatively, the rolls could be mounted with staggered chevrons.